Star wheels are used on various types of automated handling lines to convey containers to and from, and within, various machines, such as rotary packaging machines. In particular, star wheels are used to convey containers between rectilinear conveyors to a rotating machine and back to a rectilinear conveyor. Such star wheels may be used with a number of containers that include bottles, cans and tins. The various rotary packaging machines may perform various functions, e.g. cleaning, filling, capping or labeling a container.
Star wheels are generally disk shaped and their periphery contains a plurality of recesses or pockets thereby forming a star-shape. Other star wheels have circular peripheries with projecting fingers to engage the containers, and the fingers lend a general star-shape to the star wheel. Star wheels rotate about a central axis and generally comprise a pair of disk-like plates centered on this axis. Recesses may be provided in the peripheries of the disks to form pockets for receiving containers therein. The star wheel is positioned on an automated handling line so that a container travelling down the handling line is received within a pocket as the star wheel rotates. The container is retained within the pocket as the star wheel rotates before being released at a defined point.
Containers are generally retained within a pocket by supporting the container between a pair of contact surfaces that urge the container against a guide rail that encircles at least part of the star wheel's periphery. A second type of star wheel provides an alternative form of support by providing pairs of jaws to grip the container about its sides. This design does not need disks to define peripheral recesses.
A star wheel may convey a container to a closely-defined point within a rotary packaging machine or along a closely-defined path through a rotary packaging machine. For example, the container may be a bottle with a narrow neck that is presented to a filling machine: when presented, the neck of the bottle must be on the correct path such that it passes exactly beneath a filling nozzle. Thus, it is important that the center of the container follows a predetermined path and that the position of the bottle in the direction of travel is accurately controlled.
In general, any automated handling line may be used to process containers of varying shapes and sizes. In the past, each star wheel could only handle containers of a specific shape and size, so this meant having to change the star wheel each time a different container was introduced onto a handling line. This is undesirable as it is both time consuming and necessitates having to keep a stock of different-sized star wheels. Attempts have been made to overcome this problem.
Such attempts are described in the patent literature, and include, but are not limited to devices described in: U.S. Pat. No. 1,981,641; U.S. Pat. No. 2,324,312; U.S. Pat. No. 3,957,154; U.S. Pat. No. 4,124,112; U.S. Pat. No. 5,029,695; U.S. Pat. No. 5,046,599; U.S. Pat. No. 5,082,105; U.S. Pat. No. 5,540,320; U.S. Pat. No. 5,590,753; U.S. Pat. No. 7,398,871 B1; U.S. 2007/0271871 A1; DE 19903319A; EP 0 355 971 B1; EP 0 401 698 B1; EP 0 412 059 B1; EP 0 659 683 B1; EP 0 894 544 A2; EP 1 663 824 B1; JP Publication JP 10035879 A; PCT WO 2005/030616 A2; PCT WO 2009/040531 A1. Adjustable guide rails are described the patent literature as well, including in the aforementioned U.S. Pat. No. 5,540,320 and PCT WO 2005/030616 A2, and in U.S. Pat. No. 7,431,150 B2 and PCT WO 2005/123553 A1.
However, such devices often have very complex mechanical arrangements for attempting to provide adjustability. Such mechanical arrangements frequently include piston type elements that move inwardly and outwardly to set the depth of the pocket for the articles being conveyed. Other devices have adjustable fingers with complicated mechanisms to adjust the orientation of the fingers. Still other devices have multiple rotating disks with locking pins that limit the size and shape of the pockets that can be formed for the articles being conveyed, particularly the depth of the pockets. The search for improved star wheels has, therefore, continued. In particular, it is desirable to provide a simpler device that is adjustable to fit more article shapes and sizes than prior devices, and can be automatically adjusted from a CAD program containing data on the shape of the article to be conveyed.